Prolonged gestation is largely an enigma but may be due to a defect in the hormonal milieu that leads to the onset of labour (1, 2). Indeed, the duration of preg- nancy is determined by a shift in the equilibrium between inhibitors and activators of myometrial con- tractility, so that parturition results from a complex interplay between several placental players able to influence molecular pathways driving the onset of labour (2). Corticotrophin-releasing factor (CRF) and urocortin are local peptides that may be part of the hor- monal milieu controlling uterine contractility (3).
CRF is a 41-amino acid neuropeptide expressed by gestational tissues throughout pregnancy and secreted